Frequency converter master-slave control method and system based on adaptive adjustment

Abstract

The invention discloses a frequency converter master-slave control method and system based on adaptive adjustment, and relates to the technical field of frequency converter control, and the method comprises the following steps: respectively collecting the rotating speed and torque of a master motor and a slave motor in real time through a rotating speed sensor and a torque sensor in advance, and collecting the output frequencies of a master frequency converter and a slave frequency converter; and carrying out data preprocessing on the acquired rotating speeds and torques of the main motor and the slave motor and the output frequencies of the main frequency converter and the slave frequency converter. According to the invention, the motor synchronization performance can be improved, the synchronization error is controlled within a minimum range, and the production precision and the product quality are improved; load distribution is optimized, overload or underload of the motor is avoided, the service life of equipment is prolonged, and the maintenance cost is reduced; the system stability is enhanced, stable operation of the system is ensured when communication fails or the frequency converter is abnormal, and the risk of production interruption is reduced; the energy utilization efficiency is improved, energy waste is avoided, and economic benefits and social benefits are brought.

Description

Technical Field

[0001] The present invention relates to the technical field of frequency converter control, and in particular to a frequency converter master-slave control method and system based on adaptive adjustment. Background Art

[0002] In many fields such as industrial automation production, multiple motors are often required to work together to meet complex production process requirements. As a key device for motor speed control, the master-slave control technology of the inverter is crucial to achieve synchronous operation of multiple motors, load balance distribution, and stable and reliable operation of the system.

[0003] However, the existing inverter master-slave control system has many shortcomings when facing complex and changeable working conditions. For example, when load changes suddenly, motor parameters change, or communication interference occurs, the traditional master-slave control method often has difficulty in quickly and accurately adjusting the output of the master-slave inverter, resulting in reduced motor synchronization performance, uneven load distribution, and even possible system failures, affecting the normal production.

[0004] Currently, no effective solution has been proposed for the problems in the related technologies. Summary of the invention

[0005] In view of the problems in the related art, the present invention proposes a frequency converter master-slave control method and system based on adaptive adjustment to overcome the above technical problems existing in the existing related art.

[0006] The technical solution of the present invention is achieved in this way:

[0007] In one aspect, the present invention:

[0008] A frequency converter master-slave control method based on adaptive adjustment comprises the following steps:

[0009] The speed sensor and torque sensor are used to respectively collect the speed and torque of the master motor and the slave motor in real time, and the output frequency of the master inverter and the slave inverter is collected in advance;

[0010] Perform data preprocessing on the collected speed and torque of the master motor and slave motor, and the output frequency of the master inverter and slave inverter;

[0011] Calculate the operating status index according to the rotation speed and torque of the master motor and the slave motor and the output frequency of the master inverter and the slave inverter, wherein the operating status index includes: motor synchronization error and load imbalance;

[0012] According to the operating status indicators, adaptive adjustments are made, including: synchronization error adjustment and load imbalance adjustment.

[0013] The calculation of the motor synchronization error includes the following steps:

[0014] Calculate the synchronization error ei between the slave motor and the master motor, expressed as: ei = |ωmain-ωi|;

[0015] Where n is the number of motors, ω main is the speed of the main motor, and for the i-th slave motor, its speed is ω i .

[0016] It also includes the calculation of the average synchronization error, which is expressed as:

[0017]

[0018] The change rate of the synchronization error is calculated to determine the development trend of the synchronization error, which is expressed as:

[0019] Among them, Δe i It is the change of synchronization error within the time interval Δt.

[0020] The calculation of load imbalance includes the following steps:

[0021] Get the average load torque of the motor group, expressed as:

[0022] Among them, T i is the actual load torque of each motor;

[0023] Calculate the load imbalance, expressed as:

[0024] The synchronization error adjustment includes: adjusting the output frequency of the master inverter and adjusting the tracking speed of the slave inverter, wherein;

[0025] The adjusting of the output frequency of the master inverter includes: when the synchronization error exceeds the set threshold value, if the rotation speed of the slave motor lags behind that of the master motor, increasing the output frequency of the master inverter, the rotation speed of the master motor will increase accordingly; conversely, if the rotation speed of the slave motor is ahead, reducing the output frequency of the master inverter, decelerating the master motor, driving the slave motor to decelerate, and achieving synchronization;

[0026] The adjusting of the tracking speed of the slave inverter includes: if the speed of the slave motor lags behind, increasing the tracking gain of the slave inverter so that it can follow the changes of the master inverter more quickly.

[0027] The load imbalance adjustment includes: distributing the torque output;

[0028] The torque output distribution is performed, including: if the current load imbalance is large, the torque output distribution is performed.

[0029] Another aspect of the present invention is:

[0030] A frequency converter master-slave control system based on adaptive adjustment, comprising:

[0031] The data acquisition module is used to respectively acquire the speed and torque of the master motor and the slave motor in real time through the speed sensor and the torque sensor, and to acquire the output frequency of the master inverter and the slave inverter;

[0032] A data processing module is used to pre-process the collected speed and torque of the master motor and the slave motor and the output frequency of the master inverter and the slave inverter;

[0033] An operation status index module is used to calculate the operation status index according to the rotation speed and torque of the master motor and the slave motor and the output frequency of the master inverter and the slave inverter, wherein the operation status index includes: motor synchronization error and load imbalance;

[0034] The adaptive adjustment module is used to perform adaptive adjustment according to the operating status indicators, including: synchronization error adjustment and load imbalance adjustment.

[0035] Beneficial effects of the present invention:

[0036] The present invention is based on the frequency converter master-slave control method and system with adaptive adjustment. The speed and torque of the master motor and the slave motor are respectively collected in real time by the speed sensor and the torque sensor in advance, and the output frequencies of the master frequency converter and the slave frequency converter are collected; data preprocessing is performed on the collected speed and torque of the master motor and the slave motor and the output frequencies of the master frequency converter and the slave frequency converter; the operation status index is calculated according to the speed and torque of the master motor and the slave motor and the output frequencies of the master frequency converter and the slave frequency converter; adaptive adjustment is performed according to the operation status index, which can not only improve the motor synchronization performance, control the synchronization error within a very small range, and improve the production accuracy and product quality; optimize the load distribution, avoid motor overload or underload, extend the service life of the equipment, and reduce the maintenance cost; and enhance the system stability, ensure the stable operation of the system when the communication fails or the frequency converter is abnormal, and reduce the risk of production interruption; improve the energy utilization efficiency, avoid energy waste, and bring economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1is a flow chart of a frequency converter master-slave control method based on adaptive adjustment according to an embodiment of the present invention;

[0039] Figure 2 The invention is a principle block diagram of a frequency converter master-slave control system based on adaptive adjustment according to an embodiment of the invention. DETAILED DESCRIPTION

[0040] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0041] According to an embodiment of the present invention, a frequency converter master-slave control method based on adaptive adjustment is provided.

[0042] like Figure 1 As shown, the frequency converter master-slave control method based on adaptive adjustment according to an embodiment of the present invention includes the following steps:

[0043] The speed sensor and torque sensor are used to respectively collect the speed and torque of the master motor and the slave motor in real time, and the output frequency of the master inverter and the slave inverter is collected in advance;

[0044] Perform data preprocessing on the collected speed and torque of the master motor and slave motor, and the output frequency of the master inverter and slave inverter;

[0045] Among them, data preprocessing includes: data filtering and normalization preprocessing;

[0046] Calculate the operating status index according to the rotation speed and torque of the master motor and the slave motor and the output frequency of the master inverter and the slave inverter, wherein the operating status index includes: motor synchronization error and load imbalance;

[0047] The calculation of the motor synchronization error includes the following steps:

[0048] Calculate the synchronization error e between the slave motor and the master motor i , expressed as: e i =|ω main -ω i |;

[0049] Where n is the number of motors, ω main is the speed of the main motor, and for the i-th slave motor, its speed is ω i ;

[0050] Calculate the average synchronization error, expressed as:

[0051]

[0052] The change rate of the synchronization error is calculated to determine the development trend of the synchronization error, which is expressed as:

[0053] Among them, Δe i It is the change of synchronization error within the time interval Δt.

[0054] This technical solution helps to predict the deterioration of synchronization performance in advance and take adjustment measures in time by calculating the change rate of synchronization error.

[0055] The calculation of load imbalance includes the following steps:

[0056] Get the average load torque of the motor group, expressed as:

[0057] Among them, T i is the actual load torque of each motor,

[0058] Calculate the load imbalance, expressed as:

[0059] In this technical solution, the load imbalance L reflects the degree of deviation of each motor load from the average load. The larger the percentage value, the more unbalanced the load distribution.

[0060] According to the operating status indicators, adaptive adjustments are made, including: synchronization error adjustment and load imbalance adjustment;

[0061] The synchronization error adjustment includes: adjusting the output frequency of the master inverter and adjusting the tracking speed of the slave inverter;

[0062] Wherein, adjusting the output frequency of the main inverter includes the following steps:

[0063] When the synchronization error exceeds the set threshold, if the speed of the slave motor lags behind the master motor, it means that the speed of the master motor is relatively fast. At this time, if the output frequency of the master inverter is increased, the speed of the master motor will increase accordingly. The speed change of the master motor is transmitted to the slave motor through the mechanical connection or the connection of the control system, prompting the slave motor to accelerate, thereby reducing the speed difference with the master motor and gradually restoring synchronization. Conversely, if the speed of the slave motor is ahead, reduce the output frequency of the master inverter, slow down the master motor, drive the slave motor to slow down, and achieve synchronization. For example, set the synchronization error threshold to ±5%. When it is detected that the speed of the slave motor lags behind the speed of the master motor by 7%, increase the output frequency of the master inverter by 3Hz to correct the synchronization deviation.

[0064] The following steps are included in adjusting the tracking speed of the slave inverter:

[0065] If the slave motor speed lags behind, increase the tracking gain of the slave inverter so that it can follow the changes of the master inverter more quickly. After receiving the signal from the master inverter, the slave inverter responds with a higher gain and speeds up the adjustment of its own output frequency, thereby accelerating the slave motor. For example, increase the tracking gain of the slave inverter from 0.8 to 1.2 to enhance the slave motor's ability to follow the changes in the master motor speed.

[0066] The load imbalance adjustment includes: distributing the torque output;

[0067] The torque output distribution includes the following steps:

[0068] If the current load imbalance is large, torque output distribution is performed.

[0069] If one motor is overloaded and the other motors are lightly loaded, the torque output of the master and slave inverters needs to be redistributed. For motors with heavy loads, reduce the torque output setting value of their inverters accordingly to reduce the load on the motor. For motors with light loads, increase the torque output setting value of their inverters to make them bear more load. For example, there are three motors in the system. After monitoring, it is found that motor one is overloaded, while motors two and three are lightly loaded. At this time, reduce the inverter torque output setting value corresponding to motor 1 by 10%, and increase the inverter torque output setting value corresponding to motors two and three by 8% and 7% respectively to achieve balanced load distribution.

[0070] In addition, the technical solution, when applied, performs load imbalance adjustment, and also includes: adjusting according to load characteristics, including the following steps:

[0071] The characteristic curves of the motor and the load are pre-calibrated, and different types of motors and loads have different characteristics.

[0072] When adjusting the torque output, for constant torque loads, the torque output can be adjusted directly according to the preset ratio. For square torque loads such as fans and pumps, when adjusting the torque output, it is necessary to make more detailed adjustments based on the square relationship between the torque output and the speed to avoid system efficiency reduction or equipment damage due to improper torque adjustment.

[0073] Optimize communication and monitor communication status in real time. If the communication quality decreases, automatically switch the communication mode or adjust the parameters to ensure reliable data transmission;

[0074] Specifically, in application, the master inverter may be used to configure communication parameters so as to perform data exchange with the slave inverter and send the master control signal and its own operating status information to the slave inverter.

[0075] According to an embodiment of the present invention, a frequency converter master-slave control system based on adaptive adjustment is provided.

[0076] like Figure 2 As shown, the inverter master-slave control system based on adaptive adjustment according to an embodiment of the present invention includes:

[0077] The data acquisition module 1 is used to respectively acquire the speed and torque of the master motor and the slave motor in real time through the speed sensor and the torque sensor, and to acquire the output frequency of the master inverter and the slave inverter;

[0078] Data processing module 2, used for preprocessing the collected speed and torque of the master motor and the slave motor and the output frequency of the master inverter and the slave inverter;

[0079] The operating status indicator module 3 is used to calculate the operating status indicator according to the rotation speed and torque of the master motor and the slave motor and the output frequency of the master inverter and the slave inverter, wherein the operating status indicator includes:

[0080] Motor synchronization error and load imbalance;

[0081] The adaptive adjustment module 4 is used to perform adaptive adjustment according to the operating status index, including: performing synchronization error adjustment and load imbalance adjustment.

[0082] In summary, with the help of the above technical scheme of the present invention, the speed and torque of the main motor and the slave motor are respectively collected in real time by the speed sensor and the torque sensor, and the output frequency of the main inverter and the slave inverter is collected; the collected speed and torque of the main motor and the slave motor and the output frequency of the main inverter and the slave inverter are preprocessed; according to the speed and torque of the main motor and the slave motor and the output frequency of the main inverter and the slave inverter, the operation status index is calculated; according to the operation status index, adaptive adjustment is performed, which can not only improve the motor synchronization performance, control the synchronization error to a very small range, and improve production accuracy and product quality; optimize load distribution, avoid motor overload or underload, extend equipment service life, and reduce maintenance costs; and enhance system stability, ensure stable operation of the system when communication failure or inverter abnormality occurs, and reduce the risk of production interruption; improve energy utilization efficiency, avoid energy waste, and bring economic and social benefits.

[0083] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. After considering the disclosure of the specification and the examples, those skilled in the art will easily think of other embodiments of the present disclosure. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the art that are not disclosed in the present disclosure. The specification and the examples are only regarded as exemplary, and the true scope and spirit of the present disclosure are indicated by the claims.

[0084] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A frequency converter master-slave control method based on adaptive adjustment, characterized in that: The following steps are involved: The speed sensor and torque sensor are used to respectively collect the speed and torque of the master motor and the slave motor in real time, and the output frequency of the master inverter and the slave inverter is collected in advance; Perform data preprocessing on the collected speed and torque of the master motor and slave motor, and the output frequency of the master inverter and slave inverter; Calculate the operating status index according to the rotation speed and torque of the master motor and the slave motor and the output frequency of the master inverter and the slave inverter, wherein the operating status index includes: motor synchronization error and load imbalance; According to the operating status indicators, adaptive adjustments are made, including: synchronization error adjustment and load imbalance adjustment.

2. The frequency converter master-slave control method based on adaptive adjustment according to claim 1, characterized in that: Calculating the motor synchronization error includes the following steps: Calculate the synchronization error e between the slave motor and the master motor i , expressed as: e i =|ω main -ω i |; Where n is the number of motors, ω main is the speed of the main motor, and for the i-th slave motor, its speed is ω i .

3. The frequency converter master-slave control method based on adaptive adjustment according to claim 2, characterized in that: It also includes the calculation of the average synchronization error, expressed as: The change rate of the synchronization error is calculated to determine the development trend of the synchronization error, which is expressed as: Among them, Δe i It is the change of synchronization error within the time interval Δt.

4. The frequency converter master-slave control method based on adaptive adjustment according to claim 3, characterized in that: Calculating the load imbalance includes the following steps: Get the average load torque of the motor group, expressed as: Among them, T i is the actual load torque of each motor; Calculate the load imbalance, expressed as:

5. The frequency converter master-slave control method based on adaptive adjustment according to claim 1, characterized in that: Perform synchronization error adjustment, including: adjusting the output frequency of the master inverter and adjusting the tracking speed of the slave inverter, wherein; The adjusting of the output frequency of the master inverter includes: when the synchronization error exceeds the set threshold value, if the rotation speed of the slave motor lags behind that of the master motor, increasing the output frequency of the master inverter, the rotation speed of the master motor will increase accordingly; conversely, if the rotation speed of the slave motor is ahead, reducing the output frequency of the master inverter, decelerating the master motor, driving the slave motor to decelerate, and achieving synchronization; The adjusting of the tracking speed of the slave inverter includes: if the speed of the slave motor lags behind, increasing the tracking gain of the slave inverter so that it can follow the changes of the master inverter more quickly.

6. The frequency converter master-slave control method based on adaptive adjustment according to claim 5, characterized in that: Perform load imbalance adjustment, including: torque output distribution; The torque output distribution is performed, including: if the current load imbalance is large, the torque output distribution is performed.

7. A frequency converter master-slave control system based on adaptive adjustment, used in the frequency converter master-slave control method based on adaptive adjustment according to any one of claims 1 to 6, characterized in that: include: A data acquisition module (1) is used to respectively acquire the speed and torque of the master motor and the slave motor in real time through a speed sensor and a torque sensor, and to acquire the output frequency of the master inverter and the slave inverter; A data processing module (2) is used to perform data preprocessing on the collected rotation speed and torque of the master motor and the slave motor and the output frequency of the master inverter and the slave inverter; An operation status index module (3) is used to calculate the operation status index according to the rotation speed and torque of the master motor and the slave motor and the output frequency of the master inverter and the slave inverter, wherein the operation status index includes: motor synchronization error and load imbalance; The adaptive adjustment module (4) is used to perform adaptive adjustment according to the operating status index, including: performing synchronization error adjustment and load imbalance adjustment.

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